got 'Property is always "undefined"' when it's not always "undefined"

type AA = {
    a:? number,
    b:? number,
    c:? string,
}

const a: AA = {};

if(a.a !== undefined && a.b !== undefined && a.c !== undefined) {// error: Property is always "undefined"

}

try

[trusktr]

Do you guys like Flow better than TypeScript? (Just curious)

TypeScript seems to have higher usage, so if Hegel syntax is more aligned with TS, then easier for people to migrate to and adopt Hegel.

[trusktr]

That’s interesting (and sorry, off topic), the syntax c:? string, doesn’t seem to be compatible with TS (not sure if that’s a goal). In TS it is c?: string, (example).